Double-door vertical freezer

ABSTRACT

The present invention relates to a freezer  10  of the very low temperature vertical type. The freezer  10  comprises: a thermally insulating cabinet  12  comprising in turn two side walls  14  and  16 , an upper wall  18 , a lower wall  20  and a rear wall  22 ; a thermally conducting shelf  24  suitable for defining, inside the cabinet, an upper compartment  26  and a lower compartment  28 ; an upper door  30  for closing the upper compartment  26 ; and a lower door  32  for closing the lower compartment  28 . The freezer comprises a single cooling plant  34  designed to cool the upper compartment and the lower compartment. Moreover, the thermally conducting shelf defines an air-tight closure between the upper compartment and the lower compartment. Finally, the cooling plant comprises a coil circuit  36  running through the upper wall, the side walls and the rear wall of the cabinet. The coils are distributed with a variable density along the height of the cabinet.

The present invention relates to a double-door vertical freezer, in particular a very low temperature freezer.

It is known, for example in the sector of scientific laboratories, to use very low temperature freezers, i.e. freezers which are suitable for maintaining internally temperatures of between −40° C. and −80° C.

These freezers may have different configurations, for example may have a substantially horizontal or substantially vertical extension. This latter configuration offers the advantage that, for the same useful internal volume, its occupies a smaller floor area.

There exist furthermore some configurations which envisage a single refrigerated compartment closed by a single door, while other configurations envisage two separate compartments which are closed by two independent doors. This latter configuration is able to limit the problems associated with the variations in temperature which are recorded inside the refrigerated compartments upon opening the door. The double door and the double internal compartment allow, for example, separation of the samples which must be stored for a long period of time from those which must be stored for a shorter period of time. In this case, the latter samples may be placed in the compartment where the door is opened more frequently, while the other samples may be kept in an environment which comes into contact with the exterior less frequently and therefore is less exposed to variations in temperature.

Moreover, the double door allows, by means of the use of keys or other means for controlling access, two different users to have a specific dedicated space, without the activity of one interfering with the activity of the other one.

The configuration described above of the double-compartment and double-door vertical freezer is at present achieved by means of two different constructional designs. These constructional designs, although widely used, are however not without drawbacks.

A first constructional design envisages the substantial arrangement on top of one another, within a single cabinet, of two different freezers which are independent of each other. In this design, therefore, there is a clear duplication of the plants and apparatus associated with cooling of the internal compartments. This obviously results in a substantial increase in the freezer production and operating costs.

A second constructional design envisages instead the division, into two, of the internal compartment and of the door of a conventional vertical freezer. This design envisages that, in order to ensure a temperature of the two compartments which is as uniform as possible, a communication channel between the two compartments is maintained so that it is possible to establish an airflow between one compartment and the other one. This communication channel between the two compartments constitutes a potential path via which the samples stored in the upper compartment and the samples stored in the lower compartment may contaminate each other.

The object of the present invention is therefore to overcome at least partly the drawbacks mentioned above with reference to the prior art.

In particular, one task of the present invention is to provide a double-door freezer which ensures complete isolation between the upper compartment and the lower compartment and which at the same time ensures temperatures which are substantially the same in both compartments.

Another task of the present invention is to provide a double-door freezer which is able to ensure lower production and operating costs.

The abovementioned object and tasks are achieved by a double-door freezer according to claim 1.

The characteristic features and further advantages of the invention will emerge from the description provided hereinbelow, of some examples of embodiment, provided by way of a non-limiting example, with reference to the accompanying drawings in which:

FIG. 1 shows a first perspective view of a freezer according to the invention;

FIG. 2 shows a second perspective view of a freezer according to the invention;

FIG. 3 shows a third perspective view of a freezer according to the invention where the doors have been removed for greater clarity;

FIG. 4 shows a transparent perspective view of a freezer according to the invention in which part of the cooling plant is shown.

With reference to the accompanying figures, 10 denotes in its entirety a very low temperature vertical freezer according to the invention. The freezer 10 comprises:

-   -   a thermally insulating cabinet 12 comprising in turn two side         walls 14 and 16, an upper wall 18, a lower wall 20 and a rear         wall 22;     -   a thermally conducting shelf 24 suitable for defining, inside         the cabinet 12, an upper compartment 26 and a lower compartment         28;     -   an upper door 30 for closing the upper compartment 26; and     -   a lower door 32 for closing the lower compartment 28.

The freezer 10 according to the invention comprises a single cooling plant 34 designed to cool the upper compartment 26 and the lower compartment 28.

Moreover, the thermally conducting shelf 24 defines an air-tight closure between the upper compartment 26 and the lower compartment 28. Finally, the cooling plant 34 comprises a coil circuit 36 running through the upper wall 18, the side walls 14 and 16 and the rear wall 18 of the cabinet 12. The coils 36 are distributed with a variable density along the height of the cabinet 12. In connection with the present description the expression “very low temperature”, as conventionally used in the sector, is understood as meaning a temperature of between −40° C. and −80° C.

The density of the coils 36 may be defined in various manners, for example as the ratio between the overall length of the linear extension of the coils which travel along a wall and the area of the wall itself. As the person skilled in the art may easily understand, this definition may be applied also to surfaces smaller than the entire wall, but cannot be meaningfully applied if the surfaces in question are very small.

According to one embodiment of the freezer 10, the coils 36 are distributed so as to achieve a greater average density in the walls which bound the upper compartment 26 than in the walls which bound the lower compartment 28. In particular, the upper wall 18 has preferably a greater density than the side walls 14 and 16 and the rear wall 22.

According to some embodiments of the freezer 10, the volume of the upper compartment 26 is smaller than or equal to the volume of the lower compartment 28 and the extension of the coils around the upper compartment 26 is greater than or equal to the extension of the coils 36 around the lower compartment 28.

According to one embodiment of the freezer 10, the coils are distributed in the side walls 14 and 16 and in the rear wall 22 so as to have an almost constant average density along the section which bounds the upper compartment 26 and so as to have a variable density along the section which bounds the lower compartment 28. In particular, the density increase preferably from the bottom towards the top of the lower compartment 28.

According to some embodiments of the freezer 10, more than half of the coils 36 extend around the upper compartment 26. According to the embodiment of the freezer 10 shown in FIG. 4, 54% of the total of the coils extend around the upper compartment 26 and the remaining 46% extend around the lower compartment 28.

With such a distribution of the coil density, it is possible to exploit in an optimum manner the natural convention which tends, as a result of gravity, to displace the cold air downwards.

As mentioned above, the shelf 24 defines an air-tight closure between the upper compartment 26 and the lower compartment 28. This seal may be achieved, for example, by means of a silicone bead and prevents any mutual contamination of the samples stored in the two compartments. In this respect, the fact that the shelf 24 is thermally conducting, makes it easier to achieve a uniform temperature inside the two compartments even when there is no circulating air flow. As already mentioned, according to some embodiments of the freezer 10, the overall internal volume is divided up differently between the upper compartment 26 and the lower compartment 28, preferably so that the lower compartment 28 has a volume greater than that of the upper compartment 26. For example, in the embodiment of the accompanying figures, the volume of the upper compartment 26 constitutes 45% of the total cooled volume, while the remaining 55% is destined for the lower compartment 28. Applying this proportion, a freezer 10 according to the invention with an overall cooled volume of 800 litres has preferably an upper compartment 26 with a volume of 360 litres and a lower compartment 28 with a volume of 440 litres.

In the front view of the freezer 10, the two thermally insulating doors 30 and 32 are separated by a band 38 which is also thermally insulating.

According to one embodiment, the upper door 30 and the lower door 32 of the freezer 10 are identical to each other. Considering that the doors 30 and 32 are identical to each other, the difference in the volumes of the respective compartments 26 and 28 is due to the fact that the shelf 24 has a thickness smaller than that of the band 38 and the fact that the shelf 24 is mounted above, flush with the band 38. For this reason, the lower compartment 28 is internally higher than the upper compartment 26.

Moreover, mounting of the shelf 24 above, flush with the band 38, facilitates substantially the operations for internal cleaning of the upper compartment 26. This particular configuration of the freezer 10 is clearly visible from a comparison of FIG. 1 with FIG. 2. In FIG. 1, in fact, the view from above shows how the surface 24 is mounted flush with the band 38, while in FIG. 2 the view from below shows the difference in thickness between the shelf 24 and the band 38. This type of distribution of the volumes acts in synergy with the particular distribution of the coil density, allowing the natural convection to be exploited even more effectively.

With the particular configuration described above, where the density of the coils 36 is variable along the height of the cabinet 12 and, preferably, where the volumes of the two compartments 26 and 28 are different, it is possible to obtain, during operation, a temperature which is substantially the same in both compartments 26 and 28. Specific tests carried out by the applicant have shown how the temperatures in the two compartments 26 and 28 differ at the most by ±1° C. This difference is the same as or less than the differences which commonly occur between the two compartments of conventional freezers with air circulation.

According to one embodiment, the freezer 10 also comprises control means for allowing separate access to the two compartments 26 and 28. For example, each of the two doors 30 and 32 may be protected by an independent control system based on identification of the user by means of an electronic key. A control system of this type is already used by the applicant on other devices with the trade name Bioguard®. By means of this system, the users may be provided with a programmable electronic key (for example a card) which allows access to only one compartment or to both compartments.

In the light of the above description it will be clear to the person skilled in the art how the freezer according to the invention is able to overcome the drawbacks mentioned above with reference to the prior art.

In particular, in the light of all that described above, it will be clear how with the freezer 10 according to the invention it is possible to obtain a temperature which is substantially the same inside the two compartments 26 and 28, without at the same time the risk of mutual contamination and without the need for duplication of the refrigeration plant.

With regard to the abovementioned embodiments of the double-door freezer, the person skilled in the art may, in order to satisfy specific requirements, make modifications to and/or replace elements described with equivalent elements, without thereby departing from the scope of the accompanying claims. 

1-14. (canceled)
 15. A very low temperature vertical freezer, comprising: a thermally insulating cabinet comprising two side walls, an upper wall, a lower wall, and a rear wall; a thermally conducting shelf suitable for defining, inside said cabinet, an upper compartment and a lower compartment; an upper door for closing the upper compartment; a lower door for closing the lower compartment; wherein the freezer comprises a single cooling plant designed to cool the upper compartment and the lower compartment; the thermally conducting shelf forms an air-tight closure between the upper compartment and the lower compartment; and the cooling plant comprises a coil circuit running through the upper wall, the side walls, and the rear wall of the cabinet, coils of the coil circuit being distributed with variable density along a height of the cabinet.
 16. The freezer according to claim 15, wherein volume of the upper compartment is smaller than or equal to volume of the lower compartment, and wherein extension of the coils around the upper compartment is greater than or equal to the extension of the coils around the lower compartment.
 17. The freezer according to claim 15, wherein the cooling plant is designed to cool the upper and lower compartments to a temperature of between −40° C. and −80° C.
 18. The freezer according to claim 15, wherein the coils are distributed in the walls bounding the upper compartment with a greater average density than in the walls bounding the lower compartment.
 19. The freezer according to claim 15, wherein the upper wall has a density of the coils greater than density of the coils in the side walls and in the rear wall.
 20. The freezer according to claim 15, wherein the coils are distributed in the side walls and in the rear wall in such a way so as to have an almost constant average density along a section bounding the upper compartment and in such a way so as to have a variable density along the section bounding the lower compartment.
 21. The freezer according to claim 20, wherein density of the coils increases from bottom to top of the lower compartment.
 22. The freezer according to claim 15, wherein 54% of total of the coils extend around the upper compartment and remaining 46% of the total of the coils extend around the lower compartment.
 23. The freezer according to claim 15, wherein the air-tight closure between the upper compartment and the lower compartment is obtained by means of a silicone bead.
 24. The freezer according to claim 15, wherein overall inner volume of the freezer is divided up differently between the upper compartment and the lower compartment.
 25. The freezer according to claim 24, wherein volume of the upper compartment is about 45% of total volume cooled by the freezer, while volume of the lower compartment is about 55% of the total volume cooled by the freezer.
 26. The freezer according to claim 15, wherein the upper door and the lower door are identical to each other.
 27. The freezer according to claim 15, further comprising a thermally insulating band between the two upper and lower doors, the shelf having a smaller thickness than the band and being mounted above, flush with the band.
 28. The freezer according to claim 15, further comprising control means for allowing separate access to the upper and lower compartments. 